1. Field of the Invention
This invention relates to systems which vent positive air pressures, particularly within an air conditioned vehicle passenger space.
2. Description of Related Art
It is known that internal vehicle passenger compartment air pressure often becomes greater than the air pressure external to the vehicle i e., a positive air pressure differential is created with respect to the atmosphere. Vehicles with air conditioning units are especially prone to this condition. Their air conditioning units are typically sealed against sources of hot external air and consequently the passenger compartment becomes relatively air tight. When a passenger attempts to close a passenger door, air pressure is created when the door is moved into sealing engagement with the vehicle body, inhibiting easy closure of that door. This can result in an inconvenient situation for the occupant. The occupant often reopens the door and closes it with increased effort. Venting the vehicle interior to the outside relieves the positive air pressure and allows the doors to be closed easily.
In the past, others have vented the passenger compartment by supplying additional air ventilation devices and pathways. These additional ventilation devices have typically been located either in the door structure or in the vehicle body structure. U.S. Pat. No. 4,691,623 to Mizusawa discloses a multicomponent valving device that is installed in a matching aperture punched into the vehicle's "B" pillar A second aperture is punched into an interior wall of the vehicle to allow the vehicle passenger compartment to communicate with outside air via the venting device. Although the addition of this or a similar device to the body structure resolves the difficulty in closing the passenger door, economic issues arise.
Manufacturing costs increase greatly when venting devices and air pathways are added to the basic body structure. Expensive new tooling is required for punching additional apertures into the body structure to accommodate the ventilation devices. More time and personnel are needed to assemble and install these multicomponent devices. Additional material is needed for the manufacture of individual components. In addition to these manufacturing costs, punched holes in the metal body parts increase the opportunity for moisture to attack and corrode the body structure.
It is desirable to vent the interior passenger space of a vehicle without introducing new apertured features to the body structure. Such venting is particularly suitable if it makes use of existing vehicle componentry without accruing significant investment or material costs. The use of existing assembly processes further enhances the desirability of such a venting device.